Python 实现日志同时输出到屏幕和文件

1. 日志输出到屏幕

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import logging

logging.basicConfig(level=logging.NOTSET, format='％(asctime)s - ％(name)s - ％(levelname)s - ％(message)s')

logging.debug('This is a debug message.')
logging.info('This is an info message.')
logging.warning('This is a warning message.')
logging.error('This is an error message.')
logging.critical('This is a critical message.')

默认的 level 是 logging.WARNING，低于这个级别的就不输出了。如果需要显示低于 logging.WARNING 级别的内容，可以引入 logging.NOTSET 级别来显示。

DEBUG - 打印全部的日志。详细的信息，通常只出现在诊断问题上。

INFO - 打印 INFO、WARNING、ERROR、CRITICAL 级别的日志。确认一切按预期运行。

WARNING - 打印 WARNING、ERROR、CRITICAL 级别的日志。表明一些问题在不久的将来，这个软件还能按预期工作。

ERROR - 打印 ERROR、CRITICAL 级别的日志。更严重的问题，软件没能执行一些功能。

CRITICAL : 打印 CRITICAL 级别。一个严重的错误，表明程序本身可能无法继续运行。

/usr/bin/python2.7 /home/strong/git_workspace/MonoGRNet/test.py
2019-06-26 16:00:45,990 - root - DEBUG - This is a debug message.
2019-06-26 16:00:45,990 - root - INFO - This is an info message.
2019-06-26 16:00:45,990 - root - WARNING - This is a warning message.
2019-06-26 16:00:45,990 - root - ERROR - This is an error message.
2019-06-26 16:00:45,990 - root - CRITICAL - This is a critical message.

Process finished with exit code 0

2. 日志输出到文件

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import logging
import os.path
import time

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)

time_line = time.strftime('％Y％m％d％H％M', time.localtime(time.time()))

print(os.getcwd())
log_path = os.path.dirname(os.getcwd()) + '/'
logfile = log_path + time_line + '.log'

handler = logging.FileHandler(logfile, mode='w')
handler.setLevel(logging.INFO)

formatter = logging.Formatter("％(asctime)s - ％(filename)s[line:％(lineno)d] - ％(levelname)s: ％(message)s")
handler.setFormatter(formatter)

logger.addHandler(handler)

logger.debug('This is a debug message.')
logger.info('This is an info message.')
logger.warning('This is a warning message.')
logger.error('This is an error message.')
logger.critical('This is a critical message.')

/usr/bin/python2.7 /home/strong/git_workspace/MonoGRNet/test.py
/home/strong/git_workspace/MonoGRNet

Process finished with exit code 0

201906261627.log

2019-06-26 16:27:26,899 - test.py[line:30] - INFO: This is an info message.
2019-06-26 16:27:26,899 - test.py[line:31] - WARNING: This is a warning message.
2019-06-26 16:27:26,899 - test.py[line:32] - ERROR: This is an error message.
2019-06-26 16:27:26,899 - test.py[line:33] - CRITICAL: This is a critical message.

3. 日志同时输出到屏幕和文件

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import logging
import os.path
import time

logger = logging.getLogger(__name__)
logger.setLevel(level=logging.DEBUG)

time_line = time.strftime('％Y％m％d％H％M', time.localtime(time.time()))

print(os.getcwd())
log_path = os.path.dirname(os.getcwd()) + '/'
logfile = log_path + time_line + '.log'

handler = logging.FileHandler(logfile, mode='w')
handler.setLevel(logging.INFO)

formatter = logging.Formatter("％(asctime)s - ％(filename)s[line:％(lineno)d] - ％(levelname)s: ％(message)s")
handler.setFormatter(formatter)

console = logging.StreamHandler()
console.setLevel(logging.WARNING)

logger.addHandler(handler)
logger.addHandler(console)

logger.debug('This is a debug message.')
logger.info('This is an info message.')
logger.warning('This is a warning message.')
logger.error('This is an error message.')
logger.critical('This is a critical message.')

/usr/bin/python2.7 /home/strong/git_workspace/MonoGRNet/test.py
/home/strong/git_workspace/MonoGRNet
This is a warning message.
This is an error message.
This is a critical message.

Process finished with exit code 0

201906261636.log

2019-06-26 16:36:38,385 - test.py[line:34] - INFO: This is an info message.
2019-06-26 16:36:38,385 - test.py[line:35] - WARNING: This is a warning message.
2019-06-26 16:36:38,385 - test.py[line:36] - ERROR: This is an error message.
2019-06-26 16:36:38,385 - test.py[line:37] - CRITICAL: This is a critical message.

来源：https://blog.csdn.net/chengyq116/article/details/93765575